The present invention relates to knitting machines.
More particularly, the invention relates to a method of, and an arrangement for, selecting the operating needles in a knitting machine.
German Allowed Application DE-AS No. 1,044,337 discloses a knitting machine having sequentially arranged pairs of needle beds and orbiting carriages. The selection of the needles which are to knit in accordance with a predetermined pattern, is made by pattern wheels which are mounted on the respective carriages. During each orbit of the respective carriage the associated pattern wheel rolls on a stationary pattern bed and thus becomes programmed. Thereafter, the pattern wheel rolls on the needle beds and thus transmits the pattern selection made by the pattern bed to the needles of the needle beds. Inherent in all pattern wheels, however, is the limitation that they permit only very limited kinds of patterns to be knitted; more elaborate patterns cannot be made.
Since, however, there is a strong demand for such more elaborate patterns, the prior art has evolved two alternatives. From GDR Pat. No. DC 24,031 and from FRG Pat. No. DE 1,635,968 it is known to associate each needle (respectively each plunger) with an individual electromagnet which is energized from a stationary control unit in accordance with a predetermined pattern. According to the other solution, disclosed in FRG Pat. No. DE 2,010,973, the movable carriage is provided with a few electromagnetic needle selectors which are usually energized via trailing cables from a stationary control unit in accordance with the desired pattern.
The first proposal has not found much interest in the industry, since the use of a separate electromagnet for each of the many needles makes the machine complicated and expensive. It is therefore the second proposal which is usually found in practical use. However, heretofore it was not considered possible to use this proposal on flat-knitting machines with sequentially arranged pairs of needle beds and orbiting carriages, using trailing electrical cables.
For this type of machine, therefore, it is considered necessary to find a different solution. Sliding contacts, known from German Published application OS No. 2,658,588 were considered unsuitable since control signals transmitted via such sliding contacts are often distorted or otherwise changed. Electro-optical control of the needle selectors on the carriage (German Published application OS No. 2,114,013), and the use of a stationary radio transmitter and a receiver on the carriage (German Published application OS No. 2,060,942), are both complicated and expensive and were therefore ruled out.